Serviceable Hearing Preservation Research Articles

Vestibular Schwannoma Koos Grade I International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS-K1 Study.

This investigation evaluates the safety and efficacy of stereotactic radiosurgery (SRS) vs observation for Koos grade I vestibular schwannomas (VS). In a multicenter study, we retrospectively analyzed data of patients with Koos grade I VS who underwent SRS (SRS group) or were observed (observation group). Propensity score matching was used to equilibrate demographics, tumor size, and audiometric data across groups. The outcome analyzed included tumor control, preservation of serviceable hearing, and neurological function. The study matched 142 patients, providing a median follow-up period of 36 months. SRS significantly enhanced tumor control compared with observation, with a 100% control rate at both 5- and 8-year marks in the SRS group vs 48.6% and 29.5% in the observation group at the same time intervals, respectively (P < .001). Preservation of serviceable hearing outcomes between groups showed no significant difference at 5 and 8 years, ensuring a comparable quality of auditory function (SRS 70.1% vs observation 53.4% at 5 years; P = .33). Furthermore, SRS was associated with a reduced likelihood of tinnitus (odds ratio [OR] = 0.46, P = .04), vestibular dysfunction (OR = 0.17, P = .002), and overall cranial nerve dysfunction (OR = 0.49, P = .03) at last follow-up. SRS management of patients with Koos grade I VS was associated with superior tumor control and reduced odds for cranial nerve dysfunction, while not compromising hearing preservation compared with observation. These findings support the safety and efficacy of SRS as a primary care approach for this patient population.

Vestibular Schwannoma Koos Grade II International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS-K2 Study.

This study assessed the efficacy and safety of stereotactic radiosurgery (SRS) in comparison with watchful waiting for managing Koos grade II vestibular schwannomas (VS). A retrospective, multicentric analysis was conducted, focusing on patients with Koos grade II VS who either received SRS (SRS group) or were observed (observation group). To ensure comparability between groups, propensity score matching was used, including factors such as demographic characteristics, tumor dimensions, and hearing assessments. The primary end points examined were tumor control, maintenance of serviceable hearing, and neurological outcomes. A total of 92 patients were equally matched across both cohorts, with a median follow-up of 37 months for the SRS group and 27.5 months for those observed. The SRS cohort exhibited superior tumor control over observation across 3, 5, and 8 years, achieving a 100% control rate vs 47.9%, 40.1%, and 34.3% for the observation group at these time intervals, respectively (P < .001). Serviceable hearing preservation rates were comparable between the 2 groups throughout 3, 5, and 7 years (72.9% for SRS vs 65.4% for observation at 3 years; P = .86). Moreover, SRS management correlated with a lower incidence of vestibular symptoms (odds ratio = 0.11, P = .002), with no significant disparity in the deterioration of cranial nerve (CN) V or CN VII functions. Notably, the likelihood of experiencing any CN impairment was significantly diminished in the SRS cohort (odds ratio = 0.47, P = .04). For patients with Koos grade II VS, SRS offers superior tumor control rate and a lower risk of CN dysfunction without sacrificing hearing preservation.

Chronological characterization of hearing preservation after radiosurgery for vestibular schwannoma: a comprehensive meta-analysis.

Hearing outcomes following Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) are multifactorial and poorly characterized in prior literature. In this study the authors evaluated hearing outcomes chronologically to identify prognostic factors of serviceable hearing preservation (HP) rates following GKRS for VS. Six medical databases were queried according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies reported VS treated with single-fraction GKRS and included the HP rate following GKRS. HP was defined as a postoperative Gardner-Robertson score ≤ 2 among patients with preoperative serviceable hearing. A meta-analysis with random-effects modeling was performed for variables of interest. Data from 42 articles with a total of 6582 patients were analyzed; the average age of patients was 54 years and the average follow-up time was 68 months. The pooled proportion of preoperative serviceable hearing was 76%, and the pooled HP rate was 60% at the last follow-up visit. At < 5 years after GKRS, age was significantly correlated with HP on both continuous and categorical analyses (p = 0.001 and p = 0.011, respectively). Between 5 and < 10 years of follow-up, HP was associated with a radiation dose of 12.5 Gy, but not with age or tumor volume. At ≥ 10 years after radiosurgery, a significant negative correlation was seen between marginal radiation dose and HP on both continuous and categorical analyses (p = 0.001 and p = 0.021, respectively). This meta-analysis identifies age and radiation dose as independent prognostic factors for HP. Age-related hearing deterioration appears to be concentrated in the first 5 years after GKRS, whereas radiation dose was associated with HP at last follow-up, between 5 and < 10 years, and at ≥ 10 years after radiosurgery. This meta-analysis offers an objective overview of the literature and a framework for clinical decision-making, with applications for treatment planning and patient counseling.

Stereotactic Radiosurgery in Primary Treatment of Sporadic Small to Medium (

To analyze the current literature regarding use of SRS as primary treatment of VS to further evaluate efficacy and treatment-related neurologic deficits. Online databases were queried to identify relevant publications from January 2001-December 2020. Full text, English articles for sporadic VS treated primarily with radiosurgery and documented hearing preservation data were reviewed. Papers that had a minimum follow-up period of less than 36 months, did not utilize radiosurgery for primary treatment, or included patients with Neurofibromatosis II were excluded. A total of 33 studies involving 4286 patients with an average follow-up of 62.5 months were included in the final analysis. All 33 studies included eligible hearing data; overall preservation of serviceable hearing was found to be 58.27%. 27 studies with 3822 eligible patients were analyzed for tumor control rates; overall, tumor control was reported in 92.98% of cases. 27 studies were analyzed for post-treatment facial nerve dysfunction which was reported in 1.53% of cases. SRS is a safe and effective primary treatment modality for sporadic vestibular schwannoma as evidenced by the present analysis. Radiosurgery is effective with regard to tumor control and hearing preservation while offering a low rate of post-treatment facial nerve dysfunction.

Repeat stereotactic radiosurgery for progressive vestibular schwannomas after primary gamma knife radiosurgery

PurposeLimited data provides guidance on the management of vestibular schwannomas (VSs) that have progressed despite primary Gamma Knife radiosurgery (GKRS). The present article reports our long-term experience after repeat GKRS for VS with sustained progression after solely primary GKRS management.MethodsA retrospective review of 1997 patients managed between 1987 and 2023 was conducted. Eighteen patients had sustained tumor progression after primary GKRS and underwent repeat GKRS. The median repeat GKRS margin dose was 11 Gy (IQR: 11–12), the median tumor volume was 2.0 cc (IQR: 1.3–6.3), and the median cochlear dose in patients with preserved hearing was 3.9 Gy (IQR: 3-4.1). The median time between initial and repeat GKRS was 65 months (IQR: 38–118).ResultsThe median follow-up was 70 months (IQR: 23–101). After repeat GKRS, two patients had further tumor progression at 4 and 21 months and required partial resection of their tumors. The 10-year actuarial tumor control rate after repeat GKRS was 88%. Facial nerve function was preserved in 13 patients who had House-Brackmann grade 1 or 2 function at the time of repeat GKRS. Two patients with serviceable hearing preservation (Gardner-Robertson grade 1 or 2) at repeat GKRS retained that function afterwards. In patients with tinnitus, vestibular dysfunction, and trigeminal neuropathy, symptoms remained stable or improved for 16/16 patients, 12/15 patients, and 10/12 patients, respectively. One patient developed facial twitching in the absence of tumor growth 21 months after repeat GKRS.ConclusionsRepeat GKRS effectively controlled tumor growth and preserved cranial nerve outcomes in most patients whose VS had sustained progression after initial primary radiosurgery.

Hearing Function after CyberKnife for Vestibular Schwannoma: A Systematic Review.

Introduction CyberKnife (CK) radiosurgery is a treatment strategy for vestibular schwannoma (VS). Objectives To evaluate hearing preservation (HP) after CK for VS. Data Synthesis The study was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, and it was registered at the International Prospective Register of Systematic Reviews (PROSPERO, under number CRD42021250300). The inclusion criteria were based on the population, intervention, comparison, outcome, timing and study design (PICOTS) strategy: population - patients with VS; intervention - CK; Comparison - none; Outcome - serviceable HP defined by Gardner and Robertson as grades I or II, or by the American Academy of Otolaryngology and Head and Neck Surgery as classes A or B; timing - mean follow-up longer than 1 year; and study design - retrospective or prospective studies. The exclusion criteria were: studies not published in English; studies published before January 2000 and after October 2021; and studies only including patients with neurofibromatosis type 2 or submitted to a previous treatment. The PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, LILACS, and IBECS databases were used and last searched on October 27th, 2021. Statistical heterogeneity was assessed using I 2 statistics. The appraisal checklist was used to assess the risk of bias in the included studies. A total of 222 studies were analyzed, and 13 were included in the synthesis, which represents 493 participants with serviceable hearing before intervention. The mean HP rate after CK using a random effects model was of 68% (95% confidence interval [95%CI]: 59-76%) at a mean follow-up of 42.96 months. Conclusion The longer follow-up period was associated with a lower HP rate after CK radiosurgery for VS in the qualitative synthesis.

Hearing preservation outcomes using direct cranial nerve eight and auditory brainstem response neuromonitoring in the resection of vestibular schwannomas.

Advancements in microsurgical technique and technology continue to improve outcomes in patients with skull base tumor. The primary cranial nerve eight monitoring systems used in hearing preservation surgery for vestibular schwannomas (VSs) are direct cranial nerve eight monitoring (DCNEM) and auditory brainstem response (ABR), although current guidelines are unable to definitively recommend one over the other due to limited literature on the topic. Thus, further research is needed to determine the utility of DCNEM and ABR. The authors performed a retrospective cohort study and created an interactive model that compares hearing preservation outcomes based on tumor size in patients receiving ABR+DCNEM and ABR-only monitoring. Twenty-eight patients received ABR+DCNEM and 72 patients received ABR-only monitoring during VS hearing preservation surgery at a single tertiary academic medical center between January 2008 and November 2022. Inclusion criteria consisted of adult patients with a preoperative American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification of A or B. Tumor size was measured as the maximal medial to lateral length, including the internal auditory canal component. Overall hearing preservation (word recognition score [WRS] > 0%) was achieved in 31 patients with ABR-only monitoring (43.1%) and in 18 patients with ABR+DCNEM (64.3%). Serviceable hearing preservation (AAO-HNS class A or B) was attained in 19 patients with ABR-only monitoring (26.4%) and in 11 patients with ABR+DCNEM (39.3%). There was no difference in overall hearing preservation between the two groups (p = 0.13). Change in tumor size was not associated with the odds of serviceable hearing preservation for the ABR-only group (p = 0.89); however, for ABR+DCNEM, there was some indication of an interaction between tumor size and the association of ABR+DCNEM versus ABR-only monitoring, with the odds of serviceable hearing preservation at p = 0.089. Furthermore, with ABR+DCNEM, every 0.5-cm increase in tumor size was associated with a decreased odds of serviceable hearing preservation on multivariable analysis (p = 0.05). For both overall and serviceable hearing preservation, a worse preoperative AAO-HNS classification was associated with a decreased odds of preservation (OR 0.43, 95% CI 0.19-0.97, p = 0.042; OR 0.17, 95% CI 0.053-0.55, p = 0.0031, respectively). The result of this interactive model study proposes that there may be a higher chance of hearing preservation when using ABR+DCNEM rather than ABR alone for smaller tumors, with that relationship reversing as tumor size increases.

Vestibular Schwannoma International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS Study

BackgroundThe present study assesses the safety and efficacy of stereotactic radiosurgery (SRS) versus observation for Koos grade I and II vestibular schwannoma (VS), benign tumors affecting hearing and neurological function. MethodsThis multicenter study analyzed data from Koos grade I and II VS patients managed with SRS (SRS group) or observation (observation group). Propensity score matching balanced patient demographics, tumor volume, and audiometry. Outcomes measured were tumor control, serviceable hearing preservation (SHP), and neurological outcomes. ResultsIn 125 matched patients in each group with a 36-month median follow-up (p=0.49), SRS yielded superior 5- and 10-year tumor control rates (99%, CI: 97.1%-100%, and 91.9%, CI: 79.4%-100%) vs. observation (45.8%, CI: 36.8%-57.2%, and 22%, CI: 13.2%-36.7%; p<0.001). SHP rates at 5 and 9 years were comparable (SRS 60.4%, CI: 49.9%-73%, vs. observation 51.4%, CI: 41.3%-63.9%, and SRS 27%, CI: 14.5%-50.5%, vs. observation 30%, CI: 17.2%-52.2%; p=0.53). SRS were associated with lower odds of tinnitus (OR=0.39, p=0.01), vestibular dysfunction (OR=0.11, p=0.004), and any cranial nerve palsy (OR=0.36, p=0.003), with no change in cranial nerves V or VII (p>0.05). Composite endpoints of tumor progression and/or any of the previous outcomes showed significant lower odds associated with SRS compared to observation alone (p < 0.001). ConclusionSRS management in matched cohorts of Koos grade I and II VS patients demonstrated superior tumor control, comparable hearing preservation rates, and significantly lower odds of experiencing neurological deficits. These findings delineate the safety and efficacy of SRS in in the management of this patient population.

Hearing preservation after stereotactic radiosurgery for sporadic intracanalicular vestibular schwannomas classified as Koos grade 1.

The mechanism of hearing loss following stereotactic radiosurgery (SRS) for vestibular schwannomas (VSs) remains unclear. There is conflicting evidence regarding cochlear nerve damage by transient volume expansion of VSs after radiosurgery and radiation-induced cochlear damage. This study aimed to investigate whether there is a specific patient population that can achieve definite hearing preservation after SRS for VSs. A total of 37 consecutive patients with sporadic unilateral intracanalicular VSs and serviceable hearing (Gardner-Roberson [G-R] class I or II) were treated with SRS from 2009 to 2023. This is a retrospective study. Survival analysis with Cox regression for hearing deterioration was performed. The median age was 55 years old. The median tumor volume was 0.089 cm3 , and the median marginal dose was 12.0 Gy. Nonserviceable hearing deterioration occurred in 9 patients (24.3%), with a median onset of 11.9 months after SRS. The actuarial rates of serviceable hearing preservation were 86%, 82%, and 70% at 1, 2, and 3 years after SRS, respectively. In a multivariate analysis, only baseline pure tone average > 30 dB increased the risk of nonserviceable hearing deterioration with significant hazard ratio. There were 13 patients with petit VSs whose tumor volume was smaller than 0.05 cm3 , and 11 of them were treated by a 4-mm single shot with a marginal dose of 12 Gy. None of the 13 patients had nonserviceable hearing deterioration. Petit VSs that can be treated with 4-mm single or double shots with a marginal dose of 12 Gy may achieve hearing preservation after SRS.

Intraoperative cochlear nerve monitoring in microvascular decompression of hemifacial spasm and resection of vestibular schwannoma

Objective: To analyze the application of direct cochlear nerve monitoring technology-cochlear nerve action potential (CNAP) monitoring in resection of vestibular schwannoma (VS) and to compare with which in microvascular decompression (MVD) of hemifacial spasm (HFS), in order to provide reference for identification of the cochlear nerve during VS resection surgery and predicting postoperative hearing preservation. Methods: From June 2018 to March 2022, patients with facial spasm and vestibular schwannoma who underwent retrosigmoid approach surgery at the Chinese PLA General Hospital were collected. Before surgery, there were a total of 11 HFS patients and 30 VS patients. Before surgery, the former had hearing level of class A(AAO-HNS), while the latter had serviceable hearing (AAO-HNS class A-B), with a maximum tumor diameter of≤20 mm. CNAP combined with Auditory Brainstem Response (ABR) monitoring was performed during surgery. SPSS 23.0 software was used to analyze the differences of ABR and CNAP parameters between the two groups. Results: The preoperative ABR test in the VS group showed that the latency of wave V and I-V interval were significantly prolonged compared to the HFS group (t=8.36, P<0.001; t=4.61, P<0.001).In VS group, all tumors were totally removed with preserved facial nerve function (House-Brackmann grade Ⅰ-Ⅱ). The serviceable hearing preservation rate was 63.3%. In the HFS group, the initial CNAP waveforms were triphasic and biphasic, with N1 wave latency of (4.32±0.37) ms and amplitude of 25.20 [15.63, 35.40]μV. The distribution of CNAP waveforms before tumor resection in the VS group was the same as that in the HFS group, and which in the hearing preservation group after surgery was also the same. Compared with the HFS group, the latency of N1 wave was prolonged (t=2.670, P=0.011;t=4.584, P<0.001), and the amplitude of N1 wavein the VS group before tumor resection was lower (Z=-3.001, P=0.003). The amplitude of N1 wave in the hearing preservation group after surgery was 20.20 [6.23, 40.90] μV,which was significantly higher than that before tumor resection (Z=-2.133, P=0.033), but there was no statistically significant difference compared to the HFS group (Z=-0.495, P=0.621). Conclusions: The reference range of CNAP in normal hearing population can be preliminarily obtained by the analysis of CNAP in MVD surgery. The latency of N1 wave in VS patients is prolonged and the amplitude of N1 wave is decreased due to tumor compression. The CNAP waveform combined with the change of N1 wave amplitude can provide reference for intraoperative mapping of the cochlear nerve and prediction of postoperative hearing preservation.

Stereotactic Radiosurgery and Radiotherapy for Vestibular Schwannoma in NF2-Related Schwannomatosis.

To determine the long-term control rates and hearing outcomes for growing vestibular schwannoma in NF2-related schwannomatosis (NF2) treated with stereotactic radiosurgery (SRS) and fractionated radiotherapy (FRT). Retrospective review of all patients treated with SRS/FRT between 1986 and2021 from a tertiary NF2 unit. Overall tumor control was defined as: (1) growth control (growth failure was defined as growth in any dimension of 3 millimetres or more from baseline post-SRS/FRT), and (2) treatment control (no need for further intervention). Loss of serviceable hearing was defined as a drop in speech discrimination score below 50% after SRS/FRT. There were 81 cases, with a mean duration of follow-up of 125 months. Overall control rate was 72% (58/81), with 80% (65/81) growth control and 74% (60/81) treatment control. There was a 5-year actuarial survival of 77% and 10-year survival of 71%. Forty-three percent (30/69) of cases did not have serviceable hearing at baseline. Of those remaining, 49% (19/39) preserved serviceable hearing during follow-up at a mean of 106 months. Actuarial survival for preservation of serviceable hearing at 5 and 10 years was 69% and 53%. There were poorer outcomes with increasing genetic severity, and with baseline tumor size >3 cm. No cases of SRS/FRT-related malignancy were identified at a mean follow-up of 10 years. Stereotactic radiosurgery/fractionated radiotherapy are an effective option to treat growing vestibular schwannoma in patients with NF2 with the potential for hearing preservation in a proportion of patients. 4-Case Series Laryngoscope, 134:2364-2371, 2024.

Vestibular Schwannoma Stereotactic Radiosurgery in Octogenarians: Case Series.

The management of octogenarians with vestibular schwannomas (VS) has received little attention. However, with the increase in octogenarian population, more effort is needed to clarify the value of stereotactic radiosurgery (SRS) in this population. The aim of this study was to evaluate the safety and efficacy of SRS in this patient age group. A retrospective study of 62 patients aged 80 years or older who underwent single-session SRS for symptomatic VS during a 35-year interval was performed. The median patient age was 82 years, and 61.3% were male. SRS was performed as planned adjuvant management or for delayed progression after prior partial resection in 5 patients. SRS resulted in a 5-year tumor control rate of 95.6% with a 4.8% risk of adverse radiation effects (ARE). Tumor control was unrelated to patient age, tumor volume, Koos grade, sex, SRS margin dose, or prior surgical management. Four patients underwent additional management including 1 patient with symptomatic progression requiring surgical resection, 2 patients with symptomatic hydrocephalus requiring cerebrospinal fluid diversion, and 1 patient whose tumor-related cyst required delayed cyst aspiration. Three patients developed ARE, including 1 patient with permanent facial weakness (House-Brackmann grade II), 1 who developed trigeminal neuropathy, and 1 who had worsening gait disorder. Six patients had serviceable hearing preservation before SRS, and 2 maintained serviceable hearing preservation after 4 years. A total of 44 (71%) patients died at an interval ranging from 6 to 244 months after SRS. SRS resulted in tumor and symptom control in most octogenarian patients with VS.

527 Multicentric Evaluation of Stereotactic Radiosurgery for Koos Grade IV Vestibular Schwannoma in Young Patients

INTRODUCTION: Koos IV vestibular schwannoma (VS) are preferably treated by surgery. However, SRS can be an alternative for patients with contraindications or who refuse surgery. SRS for Koos IV patient younger than 45 years old has not been previously studied and could be associated with more complications. METHODS: This is a retrospective multicentric study, performed under the International Radiosurgery Research Foundation. Patients 45 years old, treated primarily for a Koos IV VS with single-session SRS, presenting with non life-threatening or incapacitating symptoms, with a follow-up ≥1 years were included. RESULTS: 176 patients with a median age of 36 years (IQR 9) and a median tumor volume of 9.3 cm3 (IQR 4.7) were included. Before SRS, serviceable hearing, facial nerve weakness (House-Brachman &gt;1) and trigeminal neuropathy was present in 51.7%, 8.5%, and 34.1% respectively. The median prescription dose was 12Gy (IQR 0.5). At a median follow-up of 3.1 years (IQR 4.5), tumor stability and regression were 38.9% and 54.3%, respectively. The 5- and 10-year progression-free rate was 90.9% and 86.7%. Early tumor enlargement occurred in 10.9% of cases. The probability of serviceable hearing preservation at 5- and 10-years was 56.8% and 45.2%, respectively. The probability of improvement or preservation of facial nerve function was 95.7% at 5 and 10-years. Adverse radiation effects were noted in 19.9%, 6 of them where managed with surgical resection of the VS. New-onset hydrocephalus occurred in 4.0%. CONCLUSIONS: Single-session SRS in selected Koos IV VS can be an alternative to surgery in a selected group of patients 45 years old. Long-term follow-up is warranted.

Long-Term Outcome of Unilateral Acoustic Neuromas With or Without Hearing Loss: Over 10 Years and Beyond After Gamma Knife Radiosurgery.

Since the long-term outcomes of 162 patients who underwent gamma knife radiosurgery (GKS) as an initial or adjuvant treatment for acoustic neuromas (ANs) with unilateral hearing loss were first reported in 1998, there has been no report of a comprehensive analysis of what has changed in GKS practice. We performed a retrospective study of the long-term outcomes of 106 patients with unilateral sporadic ANs who underwent GKS as an initial treatment. The mean patient age was 50 years, and the mean initial tumor volume was 3.68 cm3 (range, 0.10-23.30 cm3). The median marginal tumor dose was 12.5 Gy (range, 8.0-15.0 Gy) and the median follow-up duration was 153 months (range, 120-216 months). The tumor volume increased in 11 patients (10.4%), remained stationary in 27 (25.5%), and decreased in 68 patients (64.2%). The actuarial 3, 5, 10, and 15-year tumor control rates were 95.3 ± 2.1%, 94.3 ± 2.2%, 87.7 ± 3.2%, and 86.6 ± 3.3%, respectively. The 10-year actuarial tumor control rate was significantly lower in the patients with tumor volumes of ≥ 8 cm3 (P = 0.010). The rate of maintaining the same Gardner-Robertson scale grade was 28.6%, and that of serviceable hearing was 46.4%. The rates of newly developed facial and trigeminal neuropathy were 2.8% and 4.7%, respectively. The patients who received marginal doses of less than 12 Gy revealed higher tumor control failure rates (P = 0.129) and newly occurred facial or trigeminal neuropathy rates (P = 0.040 and 0.313, respectively). GKS as an initial treatment for ANs could be helpful in terms of tumor control, the preservation of serviceable hearing, and the prevention of cranial neuropathy. It is recommended to perform GKS as soon as possible not only for tumor control in unilateral ANs with hearing loss but also for hearing preservation in those without hearing loss.

The effect of tumor shape irregularity on Gamma Knife treatment plan quality and treatment outcome: an analysis of 234 vestibular schwannomas

The primary aim of Gamma Knife (GK) radiosurgery is to deliver high-dose radiation precisely to a target while conforming to the target shape. In this study, the effects of tumor shape irregularity (TSI) on GK dose-plan quality and treatment outcomes were analyzed in 234 vestibular schwannomas. TSI was quantified using seven different metrics including volumetric index of sphericity (VioS). GK treatment plans were created on a single GK-Perfexion/ICON platform. The plan quality was measured using selectivity index (SI), gradient index (GI), Paddick’s conformity index (PCI), and efficiency index (EI). Correlation and linear regression analyses were conducted between shape irregularity features and dose plan indices. Machine learning was employed to identify the shape feature that predicted dose plan quality most effectively. The treatment outcome analysis including tumor growth control and serviceable hearing preservation at 2 years, were conducted using Cox regression analyses. All TSI features correlated significantly with the dose plan indices (P < 0.0012). With increasing tumor volume, vestibular schwannomas became more spherical (P < 0.05) and the dose plan indices varied significantly between tumor volume subgroups (P < 0.001 and P < 0.01). VioS was the most effective predictor of GK indices (P < 0.001) and we obtained 89.36% accuracy (79.17% sensitivity and 100% specificity) for predicting PCI. Our results indicated that TSI had significant effects on the plan quality however did not adversely affect treatment outcomes.

Defining clinically significant tumor size in vestibular schwannoma to inform timing of microsurgery during wait-and-scan management: moving beyond minimum detectable growth.

Detection of vestibular schwannoma (VS) growth during observation leads to definitive treatment at most centers globally. Although ≥ 2 mm represents an established benchmark of tumor growth on serial MRI studies, 2 mm of linear tumor growth is unlikely to significantly alter microsurgical outcomes. The objective of the current work was to ascertain where the magnitude of change in clinical outcome is the greatest based on size. A single-institution retrospective review of a consecutive series of patients with sporadic VS who underwent microsurgical resection between January 2000 and May 2020 was performed. Preoperative tumor size cutpoints were defined in 1-mm increments and used to identify optimal size thresholds for three primary outcomes: 1) the ability to achieve gross-total resection (GTR); 2) maintenance of normal House-Brackmann (HB) grade I facial nerve function; and 3) preservation of serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery class A/B). Optimal size thresholds were obtained by maximizing c-indices from logistic regression models. Of 603 patients meeting inclusion criteria, 502 (83%) had tumors with cerebellopontine angle (CPA) extension. CPA tumor size was significantly associated with achieving GTR, postoperative HB grade I facial nerve function, and maintenance of serviceable hearing (all p < 0.001). The optimal tumor size threshold to distinguish between GTR and less than GTR was 17 mm of CPA extension (c-index 0.73). In the immediate postoperative period, the size threshold between HB grade I and HB grade > I was 17 mm of CPA extension (c-index 0.65). At the most recent evaluation, the size threshold between HB grade I and HB grade > I was 23 mm (c-index 0.68) and between class A/B and C/D hearing was 18 mm (c-index 0.68). Tumors within 3 mm of the 17-mm CPA threshold displayed similarly strong c-indices. Among purely intracanalicular tumors, linear size was not found to portend worse outcomes for all measures. The probability of incurring less optimal microsurgical outcomes begins to significantly increase at 14-20 mm of CPA extension. Although many factors ultimately influence decision-making, when considering timing of microsurgical resection, using a size threshold range as depicted in this study offers an evidence-based approach that moves beyond reflexively recommending treatment for all tumors after detecting ≥ 2 mm of tumor growth on serial MRI studies.

Fractionated Proton Beam Radiation Therapy and Hearing Preservation for Vestibular Schwannoma: Preliminary Analysis of a Prospective Phase 2 Clinical Trial

Management for vestibular schwannoma (VS) achieves excellent local control, and advances have increasingly focused on long-term serviceable hearing preservation. Fractionated stereotactic radiation therapy (FSRT) is associated with better hearing preservation compared to stereotactic radiosurgery (SRS). Fractionated proton beam radiation therapy (FPRT) may be associated with greater hearing preservation due to unique dosimetric properties of proton radiotherapy.A single institution, prospective, single-arm, phase 2 clinical trial was designed for patients with VS between 2010-2019. All patients received FPRT to a total dose of 50.4-54Gy relative biological effectiveness (RBE) over 28-30 fractions. The primary endpoint was serviceable hearing preservation, defined as Gardner-Robertson (GR) score 1-2, defined as Pure Tone Average (PTA) ≤50dB and Word Recognition Score (WRS) ≥50%, at 5 years compared to a historical rate of serviceable hearing preservation of 65% in patients treated with photon radiation therapy. Other audiometric measures included Otoacoustic Emissions (OAE) and Auditory Brainstem Response (ABR). Preliminary analysis was performed for 20 patients accrued with a minimum follow up of 1.0 year.Twenty patients were accrued with median follow up of 4.0 years (range 1.0-5.0 years), with a median age of 64 years, median RT dose of 50.4 Gy (RBE). Serviceable hearing preservation at 1 year was 53%, primary endpoint was not yet met. Local control at 4 years was 100%. Median cochlea D90 was lower for patients with serviceable hearing at 1 year (median 40.5 Gy (RBE) vs 46.9 Gy (RBE), P = 0.0863). V90, Dmean, Dmin, and other cochlea dosimetric measures were also generally lower, but the associations with hearing preservation at 1 year were not statistically significant. Median PTA at 1-year worsened from 42dB at baseline to 62dB (P < 0.0001), and median WRS at 1-year worsened significantly from 85% to 48% (P < 0.0001); PTA worsening developed earlier than WRS worsening. The rate of OAE absence significantly worsened from 60% at baseline to 100% at 1-year (P = 0.0156). Other audiometric measures, including contralateral PTA, ABR, tympanometry, were not independently associated with hearing preservation. Treatment was well tolerated, with low levels of acute and late-term toxicity; one patient incurred grade one CN V dysfunction, with no grade two or higher CN dysfunction.FPRT for vestibular schwannoma results in high rates of local control with comparable serviceable hearing preservation compared to historical RT series. Audiometric analyses suggest radiation-associated hearing dysfunction is manifested as early PTA worsening followed by WRS worsening.

Stereotactic radiosurgery as the first-line treatment for intracanalicular vestibular schwannomas.

This report evaluates the outcomes of stereotactic radiosurgery (SRS) as the first-line treatment of intracanalicular vestibular schwannomas (VSs). Between 1987 and 2017, the authors identified 209 patients who underwent SRS as the primary intervention for a unilateral intracanalicular VS. The median patient age was 54 years (range 22-85 years); 94 patients were male and 115 were female. Three patients had facial neuropathy at the time of SRS. One hundred fifty-five patients (74%) had serviceable hearing (Gardner-Robertson [GR] grades I and II) at the time of SRS. The median tumor volume was 0.17 cm3 (range 0.015-0.63 cm3). The median margin dose was 12.5 Gy (range 11.0-25.0 Gy). The median maximum dose was 24.0 Gy (range 15.7-50.0 Gy). The progression-free survival rates of all patients with intracanalicular VS were 97.5% at 3 years, 95.6% at 5 years, and 92.1% at 10 years. The rates of freedom from the need for any additional intervention were 99.4% at 3 years, 98.3% at 5 years, and 98.3% at 10 years. The serviceable hearing preservation rates in GR grade I and II patients at the time of SRS were 76.6% at 3 years, 63.5% at 5 years, and 27.3% at 10 years. In univariate analysis, younger age (< 55 years, p = 0.011), better initial hearing (GR grade I, p < 0.001), and smaller tumor volumes (< 0.14 cm3, p = 0.016) were significantly associated with improved hearing preservation. In multivariate analysis, better hearing (GR grade I, p = 0.001, HR 2.869, 95% CI 1.569-5.248) and smaller tumor volumes (< 0.14 cm3, p = 0.033, HR 2.071, 95% CI 1.059-4.047) at the time of SRS were significantly associated with improved hearing preservation. The hearing preservation rates of patients with GR grade I VS were 88.1% at 3 years, 77.9% at 5 years, and 38.1% at 10 years. The hearing preservation rates of patients with VSs smaller than 0.14 cm3 were 85.5% at 3 years, 77.7% at 5 years, and 42.6% at 10 years. Facial neuropathy developed in 1.4% from 6 to 156 months after SRS. SRS provided sustained tumor control in more than 90% of patients with intracanalicular VS at 10 years and freedom from the need for additional intervention in more than 98% at 10 years. Patients with initially better hearing and smaller VSs had enhanced serviceable hearing preservation during an observation interval up to 10 years after SRS.

Stereotactic radiosurgery as the primary management for patients with Koos grade IV vestibular schwannomas.

While extensive long-term outcome studies support the role of stereotactic radiosurgery (SRS) for smaller-volume vestibular schwannomas (VSs), its role in the management for larger-volume tumors remains controversial. Between 1987 and 2017, the authors performed single-session SRS on 170 patients with previously untreated Koos grade IV VSs (volumes ranged from 5 to 20 cm3). The median tumor volume was 7.4 cm3. The median maximum extracanalicular tumor diameter was 27.5 mm. All tumors compressed the middle cerebellar peduncle and distorted the fourth ventricle. Ninety-three patients were male, 77 were female, and the median age was 61 years. Sixty-two patients had serviceable hearing (Gardner-Robertson [GR] grades I and II). The median margin dose was 12.5 Gy. At a median follow-up of 5.1 years, the progression-free survival rates of VSs treated with a margin dose ≥ 12.0 Gy were 98.4% at 3 years, 95.3% at 5 years, and 90.7% at 10 years. In contrast, the tumor control rate after delivery of a margin dose < 12.0 Gy was 76.9% at 3, 5, and 10 years. The hearing preservation rates in patients with serviceable hearing at the time of SRS were 58.1% at 3 years, 50.3% at 5 years, and 35.9% at 7 years. Younger age (< 60 years, p = 0.036) and initial GR grade I (p = 0.006) were associated with improved serviceable hearing preservation rate. Seven patients (4%) developed facial neuropathy during the follow-up interval. A smaller tumor volume (< 10 cm3, p = 0.002) and a lower margin dose (≤ 13.0 Gy, p < 0.001) were associated with preservation of facial nerve function. The probability of delayed facial neuropathy when the margin dose was ≤ 13.0 Gy was 1.1% at 10 years. Nine patients (5%) required a ventriculoperitoneal shunt because of delayed symptomatic hydrocephalus. Fifteen patients (9%) developed detectable trigeminal neuropathy. Delayed resection was performed in 4% of patients. Even for larger-volume VSs, single-session SRS prevented the need for delayed resection in almost 90% at 10 years. For patients with minimal symptoms of tumor mass effect, SRS should be considered an effective alternative to surgery in most patients, especially those with advanced age or medical comorbidities.

Prediction of Hearing Preservation in Vestibular Schwannoma Surgery According to Tumor Size and Anatomic Extension.

Vestibular schwannoma (VS) surgery is feasible for various tumor sizes that are inappropriate for wait and scan or radiosurgery. The predictive value of 2 grading systems was investigated for postoperative hearing preservation (HP) in a large series. Retrospective analysis. Neurosurgical patient database of the University of Erlangen was queried between 2014 and 2017. Retrospective single-center analysis on 138 VSs operated on via a retrosigmoidal approach. The mean tumor size was 20.4 mm (SD, 7.6 mm) with fundal infiltration in 67.4%. The overall resection rate was 93.5%. Tumors were classified preoperatively by the 3-tier Erlangen grading system depending on size or the anatomically based 4-tier Koos grading system. Preoperative hearing preservation was found in 70.3% of patients and was significantly correlated to tumor size (P = .001). For Erlangen grading, a mean postoperative serviceable hearing preservation rate of 32% was achieved: 83.3% for tumors <12 mm, 30.3% for tumors between 12 and 25 mm, and 5.3% for tumors >25 mm. In contrast, according to Koos grading, postoperative serviceable hearing preservation was 100% for grade 1 tumors (meatal), 35.6% for grade 2 (cisternal), 23.1% for grade 3 (brainstem contact), and 21.7% for grade 4 (brainstem compression). Of the total cohort, 86% had normal or nearly normal postoperative facial function (House-Brackmann grades 1 and 2). Surgery on small VSs can achieve excellent hearing preservation. Different grading has a significant influence on and correlates with postoperative hearing preservation. Tumor size seems more important than anatomic relationship.